Improvement in grate-bars for furnaces



UNITED STATES PATENT OFFICE.

GUSTAVUS A. JASPER, OF BOSTON, AND GEORGE T. SHELDON, OF OHELMS- FORD,MASSACHUSETTS. A

IMPROVEMENT IN GRATEBARS FOR FURNACES.

Specification forming part of Letters Patent No. 157,287, dated December1, 1874; application filed November 13, 1874.

To all whom it may concern:

Be it known that we, GUSTAVUS A. J ASPER,

I of Boston, in the State of Massachusetts, and

GEORGE T. SHELnoN, of Ohelmsford, in said State, have invented anImprovement in Grate- Bars for Furnaces, of which the following is aspecification:

In ordinary furnace-grates, what is technically known as a grate-barconsists of three narrow or thin, but deep, bars or slabs of iron, castin one piece, and connected at intervals by cross-pieces, also forming apart of the casting. The ends of the castings rest upon supports at thebottom of the firechamber. The spaces between the slabs are the air ordraft spaces, and great difficulty has been found in the use ofsand-molds for casting grate-bars in which the air-spaces are narrow,since in such cases that part of the mold which is to form the air-spaceeasily breaks. Our invention has especial reference to this difficulty.Another advantage which results from the invention is the proper coolingof the castings, especially at the time when made, and this resultfollows even when the air-spaces are of ordinary width. When the threeslabs are cast together in one casting, the inner slab retains its heatmuch longer than the outside slabs, and thereby the slabs are liable tobecome warped relatively to each other, and the cross-pieces may becracked or broken. This is true, in a degree, every time the grate-baris heated. But in both cases our invention obviates the difficulty.

The invention consists in casting each gratebar in two pieces, onestraddling the other, as shown in the drawings.

Figure 1 is a side elevation of a single gratebar. Fig. 2is a plan of asingle grate-bar. Fig. 3 is a side elevation of the center casting ofthe same. Fig. 4 is a plan of the center casting. Fig. 5 is a plan ofthe outside castlng.

Ais the center casting, having slots ain the upper edge, as shown. B isthe outside casting, consisting of two slabs connected by crosspieces,marked 1;, forming a part of ,the casting, and loosely fitting in theslots a of the inside casting. The outside casting is made to straddleor ride upon the inner slab, as shown, thereby forming a completegrate-bar. The inner slab is cast deeper than the others, for strength,and for the same purpose has cast upon it projections or lugs cl. One ofthe outside slabs has lugs Z1, to determine the width of the air-spacebetween two adjoining sets. It follows that grates made up of bars thuscast may have air-spaces of any desired width, however narrow. The slabsof both castings, at the ends which rest upon the supports at the bottomof the fire-chamber, have slots 0, as shown, to allow air to passthrough the draftspaces at those ends.

We claim- The combination of the inner casting A and the outer castingB, substantially as described.

GUSTAVUS A. JASPER.

G. T. SHELDON.

Witnesses:

GEAs. H. SWAN, WILLIAM W. SWAN.

